Transition metal dichalcogenide based spin orbit torque memory device with magnetic insulator

ABSTRACT

A memory apparatus is provided which comprises: a stack comprising a magnetic insulating material and a transition metal dichalcogenide (TMD), wherein the magnetic insulating material has a first magnetization. The stack behaves as a free magnet. The apparatus includes a fixed magnet with a second magnetization. An interconnect is further provided which comprises a spin orbit material, wherein the interconnect is adjacent to the stack.

BACKGROUND

Perpendicular spin-orbit torque (pSOT) device is a promising replacementof an embedded static random access memory (e-SRAM). A pSOT devicecomprises a perpendicular magnetic tunneling junction (p-MTJ) stack on aspin orbit coupling (SOC) material.

However, fabricating a high quality p-MTJ stack on an SOC electrode ischallenging. For example, forming a stable synthetic anti-ferromagnet(SAF) and a high tunnel magnetoresistance (TMR) is a challenge for pSOTbased devices.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments of the disclosure will be understood more fully from thedetailed description given below and from the accompanying drawings ofvarious embodiments of the disclosure, which, however, should not betaken to limit the disclosure to the specific embodiments, but are forexplanation and understanding only.

FIG. 1A illustrates a magnetization response to applied magnetic fieldfor a ferromagnet.

FIG. 1B illustrates a magnetization response to applied magnetic fieldfor a paramagnet.

FIGS. 2A-D illustrate plots showing band diagrams of various transitionmetal dichalcogenides (TMDs).

FIG. 3A illustrates a cross-sectional view of a stack comprising amagnetic insulator and a TMD, in accordance with some embodiments.

FIG. 3B illustrates a valance band for intrinsic TMD and the stackcomprising a magnetic insulator and a TMD, in accordance with someembodiments.

FIGS. 4A-B illustrate a three-dimensional (3D) view and a correspondingcross-sectional view, respectively, of a TMD based spin orbit couplingmemory device, in accordance with some embodiments.

FIG. 4C illustrates a 3D view of a spin orbit coupling structure usedfor a TMD based spin orbit coupling memory device, in accordance withsome embodiments.

FIGS. 4D-E illustrate write and read mechanisms for the TMD based spinorbit coupling memory device, in accordance with some embodiments.

FIGS. 5A-B illustrate a 3D view and a corresponding cross-sectionalview, respectively, of a TMD based spin orbit coupling memory device, inaccordance with some other embodiments.

FIGS. 6A-C illustrate a mechanism for switching an out-of-plane TMDbased spin orbit coupling memory device (e.g. device of FIG. 4A), inaccordance with some embodiments.

FIG. 7 illustrates a cross-sectional view of TMD based spin orbitcoupling memory device coupled to a transistor and a bit line, accordingto some embodiments.

FIG. 8 illustrates a flowchart of a method for forming a TMD based spinorbit coupling memory device, according to some embodiments of thedisclosure.

FIG. 9 illustrates a smart device or a computer system or a SoC(System-on-Chip) with TMD based spin orbit coupling memory device,according to some embodiments.

DETAILED DESCRIPTION

Some embodiments describe a memory device that uses a stack oftransition metal dichalcogenide (TMD) and a magnetic insulator (MI)which together behave as a free magnet, wherein the stack is adjacent toa fixed magnet which in turn is adjacent to an interconnect comprisingmetal. In various embodiments, the stack of TMD and MI is adjacent to aninterconnect comprising a spin orbit coupling material. In someembodiments, the stack of TMD and MI form a bi-layer which is spinfilter with perpendicular magnetic anisotropy (PMA). In someembodiments, the bi-layer has in-plane magnetic anisotropy.

There are many technical effects of the various embodiments. Forexample, since the stack of TMD and MI is a spin filter with PMA (orin-plane magnetic anisotropy) and behaves as a free magnet, a basiccomponent for magnetic memories. The spin polarization of TMD/MIbi-layer is controlled by the magnetization orientation of the magneticinsulator. The orientation of the magnetic insulator can be switchedwith spin orbit torque (or spin orbit coupling), which is demonstratedto be very efficient. The spin filter also removes the need to use atunneling dielectric as used between the fixed and free magnets of anMTJ. As such, breakdown of tunneling dielectric (e.g., MgO) asexperienced during readout is avoided. The spin filter of variousembodiments also provides a high on/off ratio, which is similar to theon/off ratio of a TMD-based metal oxide semiconductor (MOS) device(e.g., approximately 10⁵). In some embodiments, the spin filter can alsobe used as an interconnect. The interconnect can be used for e-SRAM(embedded static random access memory) or e-DRAM (embedded dynamicaccess memory). Other technical effects will be evident from the variousembodiments and figures.

In the following description, numerous details are discussed to providea more thorough explanation of embodiments of the present disclosure. Itwill be apparent, however, to one skilled in the art, that embodimentsof the present disclosure may be practiced without these specificdetails. In other instances, well-known structures and devices are shownin block diagram form, rather than in detail, in order to avoidobscuring embodiments of the present disclosure.

Note that in the corresponding drawings of the embodiments, signals arerepresented with lines. Some lines may be thicker, to indicate moreconstituent signal paths, and/or have arrows at one or more ends, toindicate primary information flow direction. Such indications are notintended to be limiting. Rather, the lines are used in connection withone or more exemplary embodiments to facilitate easier understanding ofa circuit or a logical unit. Any represented signal, as dictated bydesign needs or preferences, may actually comprise one or more signalsthat may travel in either direction and may be implemented with anysuitable type of signal scheme.

The term “free” or “unfixed” here with reference to a magnet refers to amagnet whose magnetization direction can change along its easy axis uponapplication of an external field or force (e.g., Oersted field, spintorque, etc.). Conversely, the term “fixed” or “pinned” here withreference to a magnet refers to a magnet whose magnetization directionis pinned or fixed along an axis and which may not change due toapplication of an external field (e.g., electrical field, Oersted field,spin torque,).

Here, perpendicularly magnetized magnet (or perpendicular magnet, ormagnet with perpendicular magnetic anisotropy (PMA)) refers to a magnethaving a magnetization which is substantially perpendicular to a planeof the magnet or a device. For example, a magnet with a magnetizationwhich is in a z-direction in a range of 90 (or 270) degrees +/−20degrees relative to an x-y plane of a device.

Here, an in-plane magnet refers to a magnet that has magnetization in adirection substantially along the plane of the magnet. For example, amagnet with a magnetization which is in an x or y direction and is in arange of 0 (or 180 degrees) +/−20 degrees relative to an x-y plane of adevice.

The term “device” may generally refer to an apparatus according to thecontext of the usage of that term. For example, a device may refer to astack of layers or structures, a single structure or layer, a connectionof various structures having active and/or passive elements, etc.Generally, a device is a three-dimensional structure with a plane alongthe x-y direction and a height along the z direction of an x-y-zCartesian coordinate system. The plane of the device may also be theplane of an apparatus which comprises the device.

Throughout the specification, and in the claims, the term “connected”means a direct connection, such as electrical, mechanical, or magneticconnection between the things that are connected, without anyintermediary devices.

The term “coupled” means a direct or indirect connection, such as adirect electrical, mechanical, or magnetic connection between the thingsthat are connected or an indirect connection, through one or morepassive or active intermediary devices.

The term “adjacent” here generally refers to a position of a thing beingnext to (e.g., immediately next to or close to with one or more thingsbetween them) or adjoining another thing (e.g., abutting it).

The term “circuit” or “module” may refer to one or more passive and/oractive components that are arranged to cooperate with one another toprovide a desired function.

The term “signal” may refer to at least one current signal, voltagesignal, magnetic signal, or data/clock signal. The meaning of “a,” “an,”and “the” include plural references. The meaning of “in” includes “in”and “on.”

The term “scaling” generally refers to converting a design (schematicand layout) from one process technology to another process technologyand subsequently being reduced in layout area. The term “scaling”generally also refers to downsizing layout and devices within the sametechnology node. The term “scaling” may also refer to adjusting (e.g.,slowing down or speeding up—i.e. scaling down, or scaling uprespectively) of a signal frequency relative to another parameter, forexample, power supply level.

The terms “substantially,” “close,” “approximately,” “near,” and“about,” generally refer to being within +/−10% of a target value. Forexample, unless otherwise specified in the explicit context of theiruse, the terms “substantially equal,” “about equal” and “approximatelyequal” mean that there is no more than incidental variation betweenamong things so described. In the art, such variation is typically nomore than +/−10% of a predetermined target value.

Unless otherwise specified the use of the ordinal adjectives “first,”“second,” and “third,” etc., to describe a common object, merelyindicate that different instances of like objects are being referred to,and are not intended to imply that the objects so described must be in agiven sequence, either temporally, spatially, in ranking or in any othermanner.

For the purposes of the present disclosure, phrases “A and/or B” and “Aor B” mean (A), (B), or (A and B). For the purposes of the presentdisclosure, the phrase “A, B, and/or C” means (A), (B), (C), (A and B),(A and C), (B and C), or (A, B and(C).

The terms “left,” “right,” “front,” “back,” “top,” “bottom,” “ver,'under,” and the like in the description and in the claims, if any, areused for descriptive purposes and not necessarily for describingpermanent relative positions. For example, the terms “over,” “under,”“front side,” “back side,” “top,” “bottom,” “over,” “under,” and “on” asused herein refer to a relative position of one component, structure, ormaterial with respect to other referenced components, structures ormaterials within a device, where such physical relationships arenoteworthy. These terms are employed herein for descriptive purposesonly and predominantly within the context of a device z-axis andtherefore may be relative to an orientation of a device. Hence, a firstmaterial “over” a second material in the context of a figure providedherein may also be “under” the second material if the device is orientedupside-down relative to the context of the figure provided. In thecontext of materials, one material disposed over or under another may bedirectly in contact or may have one or more intervening materials.Moreover, one material disposed between two materials may be directly incontact with the two layers or may have one or more intervening layers.In contrast, a first material “on” a second material is in directcontact with that second material. Similar distinctions are to be madein the context of component assemblies.

The term “between” may be employed in the context of the z-axis, x-axisor y-axis of a device. A material that is between two other materialsmay be in contact with one or both of those materials, or it may beseparated from both of the other two materials by one or moreintervening materials. A material “between” two other materials maytherefore be in contact with either of the other two materials, or itmay be coupled to the other two materials through an interveningmaterial. A device that is between two other devices may be directlyconnected to one or both of those devices, or it may be separated fromboth of the other two devices by one or more intervening devices.

Here, multiple non-silicon semiconductor material layers may be stackedwithin a single fin structure. The multiple non-silicon semiconductormaterial layers may include one or more “P-type” layers that aresuitable (e.g., offer higher hole mobility than silicon) for P-typetransistors. The multiple non-silicon semiconductor material layers mayfurther include one or more “N-type” layers that are suitable (e.g.,offer higher electron mobility than silicon) for N-type transistors. Themultiple non-silicon semiconductor material layers may further includeone or more intervening layers separating the N-type from the P-typelayers. The intervening layers may be at least partially sacrificial,for example to allow one or more of a gate, source, or drain to wrapcompletely around a channel region of one or more of the N-type andP-type transistors. The multiple non-silicon semiconductor materiallayers may be fabricated, at least in part, with self-aligned techniquessuch that a stacked CMOS device may include both a high-mobility N-typeand P-type transistor with a footprint of a single finFET.

For the purposes of present disclosure, the terns “spin” and “magneticmoment” are used equivalently. More rigorously, the direction of thespin is opposite to that of the magnetic moment, and the charge of theparticle is negative (such as in the case of electron).

It is pointed out that those elements of the figures having the samereference numbers (or names) as the elements of any other figure canoperate or function in any manner similar to that described, but are notlimited to such.

FIG. 1A illustrates a magnetization hysteresis plot 100 for ferromagnet(FM) 101. The plot shows magnetization response to an applied magneticfield for ferromagnet 101. The x-axis of plot 100 is magnetic field ‘H’while the y-axis is magnetization ‘m’. For FM 101, the relationshipbetween ‘H’ and ‘m’ is not linear and results in a hysteresis loop asshown by curves 102 and 103. The maximum and minimum magnetic fieldregions of the hysteresis loop correspond to saturated magnetizationconfigurations 104 and 106, respectively. In saturated magnetizationconfigurations 104 and 106, FM 101 has stable magnetization. In the zeromagnetic field region 105 of the hysteresis loop, FM 101 does not have adefinite value of magnetization, but rather depends on the history ofapplied magnetic fields. For example, the magnetization of FM 101 inconfiguration 105 can be either in the +x direction or the −x directionfor an in-plane FM. As such, changing or switching the state of FM 101from one magnetization direction (e.g., configuration 104) to anothermagnetization direction (e.g., configuration 106) is time consumingresulting in slower nano-magnets response time. It is associated withthe intrinsic energy of switching proportional to the area in the graphcontained between curves 102 and 103.

In some embodiments, FM 101 is formed of CFGG (i.e., Cobalt (Co), Iron(Fe), Germanium (Ge), or Gallium (Ga) or a combination of them). In someembodiments, FM 101 comprises one or more of Co, Fe, Ni alloys andmultilayer hetero-structures, various oxide ferromagnets, garnets, orHeusler alloys. Heusler alloys are ferromagnetic metal alloys based on aHeusler phase. Heusler phases are intermetallic with certain compositionand face-centered cubic crystal structure. The ferromagnetic property ofthe Heusler alloys are a result of a double-exchange mechanism betweenneighboring magnetic ions. In some embodiments, the Heusler alloyincludes one of: Cu₂MnAl, Cu₂MnIn, Cu₂MnSn, Ni₂MnAl, Ni₂MnIn, Ni₂MnSn,Ni₂MnSb, Ni₂MnGa Co₂MnAl, Co₂MnSi, Co₂MnGa, Co₂MnGe, Pd₂MnAl, Pd₂MnIn,Pd₂MnSn, Pd₂MnSb, Co₂FeSi, Co₂FeAl, Fe₂VAl, Mn₂VGa, Co₂FeGe, MnGa, orMnGaRu.

FIG. 1B illustrates magnetization plot 120 for paramagnet 121. Plot 120shows the magnetization response to an applied magnetic field forparamagnet 121. The x-axis of plot 120 is magnetic field ‘H’ while they-axis is magnetization ‘m’. A paramagnet, as opposed to a ferromagnet,exhibits magnetization when a magnetic field is applied to it.Paramagnets generally have magnetic permeability greater or equal to oneand hence are attracted to magnetic fields. Compared to plot 100, themagnetic plot 120 of FIG. 1B does not exhibit hysteresis which allowsfor faster switching speeds and smaller switching energies between thetwo saturated magnetization configurations 124 and 126 of curve 122. Inthe middle region 125, paramagnet 121 does not have any magnetizationbecause there is no applied magnetic field (e.g., H=0). The intrinsicenergy associated with switching is absent in this case.

In some embodiments, paramagnet 121 comprises a material which includesone or more of: Platinum(Pt), Palladium (Pd), Tungsten (W), Cerium (Ce),Aluminum (Al), Lithium (Li), Magnesium (Mg), Sodium (Na), Cr₂O₃(chromium oxide), CoO (cobalt oxide), Dysprosium (Dy), Dy₂O (dysprosiumoxide), Erbium (Er), Er₂O₃ (Erbium oxide), Europium (Eu), Eu₂O₃(Europium oxide), Gadolinium (Gd), Gadolinium oxide (Gd₂O₃), FeO andFe₂O₃ (Iron oxide), Neodymium (Nd), Nd₂O₃ (Neodymium oxide), KO₂(potassium superoxide), praseodymium (Pr), Samarium (Sm), Sm₂O₃(samarium oxide), Terbium (Tb), Tb₂O₃ (Terbium oxide), Thulium (Tm),Tm₂O₃ (Thulium oxide), or V₂O₃ (Vanadium oxide). In some embodiments,paramagnet 121 comprises dopants which include one or more of: Ce, Cr,Mn, Nb, Mo, Tc, Re, Nd, Gd, Tb, Dy, Ho, Er, Tm, or Yb. In variousembodiments, the magnet can be either a FM or a paramagnet.

FIGS. 2A-D illustrate plots 200, 220, 230, and 240, respectively,showing band diagrams of various transition metal dichalcogenides(TMDs). In TMDs such as MoS₂, MoSe₂, WS₂, and WSe₂, the strongspin-orbit interaction originating from the transition metal ion's dorbitals introduces a spin split in the valence bands. The difference isthe degree of spit depends on the material for TMD. For plot 200, thespin split for MoS₂ is shown by spin-up 201 and spin-down 202. For plot220, the spin split for MoSe₂ is shown by spin-up 221 and spin-down 222.For plot 230, the spin split for WS₂ is shown by spin-up 231 andspin-down 232. For plot 240, the spin split for WSe₂ is shown by spin-up241 and spin-down 242. It should be noted that the spin-up and spin-downdirections are labeled for explanation purposes, and that their labelscan be reversed. For example, 221 illustrates spin-down while 222illustrates spin up.

FIG. 3A illustrates a cross-sectional view 300 of a stack comprising amagnetic insulator MI 301 and a TMD 302, in accordance with someembodiments. In some embodiments, MI 301 comprises one or more of: EuS(europium sulfide), EuO (europium oxide), YIG (Yttrium iron garnet suchas Y₃Fe₅O₁₂), TmIG (thulium iron garnet such as Tm₃Fe₅O₁₂), or GaMnAs(Gallium manganese arsenide). In some embodiments, TMD 302 comprises oneor more of: MoS₂ (Molybdenum disulfide), MoSe₂ (Molybdenum diselenide)WS₂ (Tungsten disulfide), WSe₂ (Tungsten diselenide), PtS₂ (Platinumdisulfide), PtSe₂ (Platinum diselenide), WTe₂ (Tungsten Ditelluride),MoTe₂ (Molybdenum Ditelluride), or graphene.

FIG. 3B illustrates plot 320 showing valance band for intrinsic TMD andthe stack comprising an MI and a TMD, in accordance with someembodiments. Here, three valance bands are shown where valance band 321is one of spin-split sub-band, valance band 322 is the other spin-splitsub-band for an intrinsic TMD, and valance band 323 is the lift ofvalance band 322 for the stack comprising MI 301 and TMD 302. Thevalance band 323 rises above valance bands 322 and 321, and over theFermi energy level E_(F) 324 resulting in a clear or pronounced split ofspin-down 325 and spin-up 326 orientations. In one example,valley-splitting of over 300 meV is seen for MoTe₂ and EuO stackedmaterials. This clear split of spin-down 325 and spin-up 326orientations is largely because of the MI layer 301 when combined withTMD 302 to form a stack. This stack can be used as a spin filter. Assuch, in a TMD/MI stack, if spin splitting is large enough, it allowstransport charge current with one specific spin polarization. Forexample, if valance band with spin “up” is lifted in a TMD/MI stack,charge current with spin “up” can flow through, but charge current withspin “down” cannot flow through.

FIGS. 4A-B illustrate a three-dimensional (3D) view 400 and acorresponding cross-sectional view 420, respectively, of a TMD basedspin orbit coupling memory device, in accordance with some embodiments.In some embodiments, the device comprises a magnetic insulator (MI) 401,TMD 402, fixed magnet 403, and spin orbit coupling interconnect 404. Thedevice forms a three-terminal device, where the first terminal iscoupled to fixed magnet 403 (directly or indirectly through an electrodeand/or a synthetic antiferromagnetic material (SAF)) while the other twoterminals are coupled to the SOC interconnect 404 (e.g., on either sideof the length of the SOC interconnect along the y-axis).

In some embodiments, MI 401 comprises one or more of: EuS (europiumsulfide), EuO (europium oxide), YIG (Yttrium iron garnet such asY₃Fe₅O₁₂), TmIG (thulium iron garnet such as Tm₃Fe₅O₁₂), or GaMnAs(Gallium manganese arsenide). In some embodiments, TMD 402 comprises oneor more of: MoS₂ (Molybdenum disulfide), MoSe₂ (Molybdenum diselenide)WS₂ (Tungsten disulfide), WSe₂ (Tungsten diselenide), PtS₂ (Platinumdisulfide), PtSe₂ (Platinum diselenide), WTe₂ (Tungsten Ditelluride),MoTe₂ (Molybdenum Ditelluride), or graphene.

In some embodiments, fixed magnet 403 has saturated magnetization M_(s)and effective anisotropy field H_(k). Saturated magnetization M_(s) isgenerally the state reached when an increase in applied externalmagnetic field H cannot increase the magnetization of the material.Anisotropy H_(k) generally refers material properties that are highlydirectionally dependent.

In some embodiments, fixed magnet 403 is a ferromagnet (FM) whichincludes materials such as: of CFGG (i.e., Cobalt (Co), Iron (Fe),Germanium (Ge), or Gallium (Ga) or a combination of them). In someembodiments, FM 403 comprises one or more of Co, Fe, Ni alloys andmultilayer hetero-structures, various oxide ferromagnets, garnets, orHeusler alloys. For example, CoFeB, FeB, CoFe, LaSrMoO₃(LSMO), Co/Pt,CoFeGd, and ferromagnetic semi-metal such as Weyl, and Heusler alloysuch as Cu₂MnAl, Cu₂MnIn, Cu₂MnSn can be used for FM 403. Heusler alloysare ferromagnetic metal alloys based on a Heusler phase. Heusler phasesare intermetallic with certain composition and face-centered cubiccrystal structure. The ferromagnetic property of the Heusler alloys area result of a double-exchange mechanism between neighboring magneticions. In some embodiments, the Heusler alloy includes one of: Cu₂MnAl,Cu₂MnIn, Cu₂MnSn, Ni₂MnAl, Ni₂MnIn, Ni₂MnSn, Ni₂MnSb, Ni₂MnGa Co₂MnAl,Co₂MnSi, Co₂MnGa, Co₂MnGe, Pd₂MnAl, Pd₂MnIn, Pd₂MnSn, Pd₂MnSb, Co₂FeSi,Co₂FeAl, Fe₂VAl, Mn₂VGa, Co₂FeGe, MnGa, or MnGaRu.

In some embodiments, fixed magnet 403 is a paramagnet. Paramagnets arenon-ferromagnetic elements with strong paramagnetism which have highnumber of unpaired spins but are not room temperature ferromagnets. Aparamagnet, as opposed to a ferromagnet, exhibits magnetization when amagnetic field is applied to it. In some embodiments, the paramagnetcomprises a material which includes one or more of: Platinum(Pt),Palladium (Pd), Tungsten (W), Cerium (Ce), Aluminum (Al), Lithium (Li),Magnesium (Mg), Sodium (Na), Cr₂O₃ (chromium oxide), CoO (cobalt oxide),Dysprosium (Dy), Dy₂O (dysprosium oxide), Erbium (Er), Er₂O₃ (Erbiumoxide), Europium (Eu), Eu₂O₃ (Europium oxide), Gadolinium (Gd),Gadolinium oxide (Gd₂O₃), FeO and Fe₂O₃ (Iron oxide), Neodymium (Nd),Nd₂O₃ (Neodymium oxide), KO₂ (potassium superoxide), praseodymium (Pr),Samarium (Sm), Sm₂O₃ (samarium oxide), Terbium (Tb), Tb₂O₃ (Terbiumoxide), Thulium (Tm), Tm₂O₃ (Thulium oxide), or V₂O₃ (Vanadium oxide).In some embodiments, the paramagnet comprises dopants which include oneor more of: Ce, Cr, Mn, Nb, Mo, Tc, Re, Nd, Gd, Tb, Dy, Ho, Er, Tm, orYb.

In some embodiments, fixed magnet 403 is an insulating (insulative) orsemi-insulating magnet, which comprises a material that includes one ormore of: Co, Fe, No, or O. In some embodiments, the insulating orsemi-insulating magnet comprises a material which includes one or moreof: Co₂O₃, Fe₂O₃, Co₂FeO₄, or Ni₂FeO₄. In some embodiments, theinsulating or semi-insulating magnet has Spinel crystal structure.

In some embodiments, fixed magnet 403 comprises at least two fixedmagnets that are coupled by a coupling layer. In some embodiments, thecoupling layer comprises one or more of: Ru, Os, Hs, Fe, or othersimilar transition metals from the platinum group of the periodic table.In some embodiments, the coupling layer(s) are removed so that the fixedmagnets of the fixed magnet structure or stack are directly connectedwith one another forming a single magnet (or a composite magnet). Acomposite magnet may be a super lattice including a first material and asecond material, wherein the first material includes one of: Co, Ni, Fe,or Heusler alloy, and wherein the second material includes one of: Pt,Pd, Ir, Ru, or Ni.

In some embodiments, fixed magnet 403 is an in-plane magnet and MI 401is also an in-plane magnetic insulator. In some embodiments, fixedmagnet 403 is an out-of-plane magnet and MI 401 is also an out-of-planemagnetic insulator. The thickness of a magnet 403 may determine itsequilibrium magnetization direction. For example, when the thickness ofthe fixed magnet 403 is above a certain threshold (depending on thematerial of the magnet, e.g. approximately 1.5 nm for CoFe), then theferromagnetic layer exhibits magnetization direction which is in-plane.Likewise, when the thickness of fixed magnet 403 is below a certainthreshold (depending on the material of the magnet), then the magnet 403exhibits magnetization direction which is perpendicular to the plane ofthe device.

Other factors may also determine the direction of magnetization. Forexample, factors such as surface anisotropy (depending on the adjacentlayers or a multi-layer composition of the ferromagnetic layer) and/orcrystalline anisotropy (depending on stress and the crystal latticestructure modification such as FCC (face centered cubic lattice), BCC(body centered cubic lattice), or L1₀-type of crystals, where L1₀ is atype of crystal class which exhibits perpendicular magnetization), canalso determine the direction of magnetization.

L1₀ is a crystallographic derivative structure of an FCC (face centeredcubic lattice) structure and has two of the faces occupied by one typeof atom and the corner and the other face occupied with the second typeof atom. When phases with the L1₀ structure are ferromagnetic, themagnetization vector usually is along the [0 0 1] axis of the crystal.Examples of materials with L1₀ symmetry include CoPt and FePt. Examplesof materials with tetragonal crystal structure and magnetic moment areHeusler alloys such as CoFeAl, MnGe, MnGeGa, and MnGa.

In some embodiments, when fixed magnet 403 is a perpendicular magnet(e.g., magnet with out-of-plane magnetization relative to a plane of adevice), fixed magnet 403 may comprise a stack of materials, wherein thematerials for the stack are selected from a group consisting of: Co andPt; Co and Pd; Co and Ni; MgO, CoFeB, Ta, CoFeB, and MgO; MgO, CoFeB, W,CoFeB, and MgO; MgO, CoFeB, V, CoFeB, and MgO; MgO, CoFeB, Mo, CoFeB,and MgO; MnxGa_(y); materials with L1₀ symmetry; and materials withtetragonal crystal structure. In some embodiments, perpendicular magnet403 is a magnet with PMA (perpendicular magnetic anisotropy) formed of asingle layer of one or more materials. In some embodiments, the singlelayer comprises of MnGa.

In some embodiments, the spin orbit coupling (SOC) material ofinterconnect 404 (or the write electrode) includes 3D materials such asone or more of β-Tantalum (β-Ta), Ta, β-Tungsten (β-W), W, Pt, Copper(Cu) doped with elements (dopants) such as Iridium, Bismuth and any ofthe elements of 3d, 4d, 5d and 4f, 5f periodic groups in the PeriodicTable which may exhibit high spin orbit coupling. In some embodiments,the SOC interconnect comprises one or more of: Pt, Ta, W, WO_(x), CuBi,BiO_(x), Bi₂Se₃, Bi₂Sb₃, SrIrO₃, or a stack of LaAlO₃ (LAO) and SrTiO₃(STO).

In some embodiments, the spin orbit material of interconnect 404includes transitions into high conductivity non-magnetic metal(s) oneither side of interconnect 404 to reduce the resistance of interconnect404. The non-magnetic metal(s)/b include one or more of: Cu, Co, α-Ta,Al, Au, Ag, graphene, CuSi, or NiSi.

In some embodiments, the spin orbit material of interconnect 404includes one or more of: graphene, TiS₂, WS₂, MoS₂, TiSe₂, WSe₂, MoSe₂,B₂S₃, Sb₂S₃, Ta₂S, Re₂S₇, LaCPS₂, LaOAsS₂, ScOBiS₂, GaOBiS₂, AlOBiS₂,LaOSbS₂, BiOBiS₂, YOBiS₂, InOBiS₂, LaOBiSe₂, TiOBiS₂, CeOBiS₂, PrOBiS₂,NdOBiS₂, LaOBiS₂, or SrFBiS₂. In some embodiments, the spin orbitmaterial of interconnect 404 includes one of a 2D material or a 3Dmaterial, wherein the 3D material is thinner than the 2D material. Insome embodiments, the spin orbit material of interconnect 404 comprisesa spin orbit material which includes materials that exhibitRashba-Bychkov effect.

In some embodiments, the 2D materials include one or more of: Mo, S, W,Se, Graphene, MoS₂, WSe₂, WS₂, or MoSe₂. In some embodiments, the 2Dmaterials include an absorbent which includes one or more of: Cu, Ag,Pt, Bi, Fr, or H absorbents. In some embodiments, the spin orbitmaterial of interconnect 404 includes materials that exhibitRashba-Bychkov effect. In some embodiments, the spin orbit material ofinterconnect 404 includes materials that exhibit Rashba-Bychkov effectcomprises materials ROCh₂, where ‘R’ includes one or more of: La, Ce,Pr, Nd, Sr, Sc, Ga, Al, or In, and where “Ch” is a chalcogenide whichincludes one or more of: S, Se, or Te. In some embodiments, when themagnets and the spin filter have in-plane magnetizations, spin orbitmaterial may comprise materials that exhibit Rashba-Edelstine effect.Such materials include one or more of: β-Tantalum (β-Ta), Ta, β-Tungsten(β-W), W, Platinum (Pt), Copper (Cu) doped with elements including on ofIridium, Bismuth or elements of 3d, 4d, 5d and 4f, 5f periodic groups,Ti, S, W, Mo, Se, B, Sb, Re, La, C, P, La, As, Sc, O, Bi, Ga, Al, Y, In,Ce, Pr, Nd, F, Ir, Mn, Pd, or Fe.

In some embodiments, the magnetic orientation of MI 401 is controlled bySOC interconnect 404 resulting in a “free” spin filter stack formed oflayers MI 401 and TMD 402. As such, MI 401 and TMD 402 together behaveas a free magnet or the switching component of the memory device. Inthis example, MI 401 has its easy axis along the plane (e.g., z plane)direction. For this type, an external field along the y-axis, Hy, orinterconnect 404 with build-in exchange bias field is applied to breakthe symmetry and achieve bipolar switching. Assuming that the drivingforce for switching originates from the spin orbit torque or spin Halleffect in interconnect 404, the critical current density Jc is given by:

$J_{c} = {\frac{2\; e\; \alpha \; M_{s}t_{F}}{h\; \theta_{SH}^{eff}}\left( {H_{k}^{eff},{{in} + \frac{H_{k}^{eff},{out}}{2}}} \right)}$

where α a is the Gilbert damping constant, e is the elementary charge, his the Dirac contact, θ_(SH) ^(eff) is the effective spin Hall angle,M_(s) is the saturation magnetization, t_(F) is the thickness of the MI401 along the z-direction, H_(k) ^(eff), in is in-plane effectiveanisotropy field, and H_(k) ^(eff), out is the out-of-plane effectiveanisotropy field of the MI 401.

In this example, the applied current I_(w) is converted into spincurrent I_(s) by SOC interconnect 404 (also referred to as the writeelectrode). This spin current switches the direction of magnetization ofthe MI 401 and thus changes the resistance of three terminal device.However, to read out the state of device, a sensing mechanism is used tosense the resistance change in the stack comprising layers 401, 402, and403. This stack is also referred to as the non-tunneling magneticjunction 421.

The non-tunneling magnetic junction 421 of various embodiments is amemory cell which is written by applying a charge current via SOCinterconnect 404. The stack of layers 401 and 402 together behave like afixed magnet (or a reference magnet). The direction of the magneticwriting in MI 401 is decided by the direction of the applied chargecurrent. Positive currents (e.g., currents flowing in the +y direction)produce a spin injection current with transport direction (along the +zdirection) and spins pointing to the +x direction. The injected spincurrent in turn produces spin torque to align the MI 401 (coupled to SOCinterconnect 404) in the +z direction. Negative currents (e.g., currentsflowing in the −y direction) produce a spin injection current withtransport direction (along the +z direction) and spins pointing to the−x direction. The injected spin current in-turn produces spin torque toalign the MI 401 (coupled to the SOC interconnect 404) in the −zdirection. In some embodiments, in materials with the opposite sign ofthe SOC effect, the directions of spin polarization and thus of the MI401 magnetization alignment are reversed compared to the above.

FIG. 4C illustrates a 3D view 430 of a spin orbit coupling structureused for a TMD based spin orbit coupling memory device, in accordancewith some embodiments.

In this example, positive charge current represented by J_(c) producesspin-front (e.g., in the +x direction) polarized current 431 andspin-back (e.g., in the −x direction) polarized current 432. Theinjected spin current J_(s) or

generated by a charge current

in the write electrode 404 is given by:

{right arrow over (I)} _(s) =P _(SHE)(w,t,λ _(sf),θ_(SHE))({right arrowover (I)} _(c) ×{circumflex over (z)})  (1)

where, the vector of spin current {right arrow over (I)}_(s)={rightarrow over (I)}_(↑)−{right arrow over (I)}_(↓) points in the directionof transferred magnetic moment and has the magnitude of the differenceof currents with spin along and opposite to the spin polarizationdirection, {circumflex over (z)} is the unit vector perpendicular to theinterface, P_(SHE) the spin Hall injection efficiency which is the ratioof magnitude of transverse spin current to lateral charge current, w isthe width of the magnet, is t the thickness of the SOC Interconnect (orwrite electrode) 404, λ_(sf) is the spin flip length in SOC interconnect404, θ_(SHE) is the spin Hall angle for SOC interconnect SOC to freemagnet layer interface. The injected spin angular momentum per unit timeresponsible for the spin torque is given by:

$\begin{matrix}{\overset{\rightharpoonup}{S} = {h\; \frac{\overset{->}{I_{s}}}{2\; e}}} & (2)\end{matrix}$

The generated spin up and down currents 431/432 are equivalent to thespin polarized current per unit area (e.g., {right arrow over (J)}_(s))given by:

{right arrow over (J)} _(s)=θ_(SHE)({right arrow over (j)} _(c)×{circumflex over (z)})  (3)

This spin to charge conversion is based on Tunnel Magneto Resistance(TMR) which is highly limited in the signal strength generated. The TMRbased spin to charge conversion has low efficiency (e.g., less thanone).

In some embodiments, switching layer 401 (e.g., MI 401) has easy axis inthe film plane (e.g., y plane) and collinear with the current along they-axis. The fixed magnet 403 also has magnetization along the y-plane.Material wise, the structures are same as those discussed above but withdifferent magnetic orientation along the same plane. In someembodiments, the easy axis is parallel to the current flowing along they axis. With the application of an external magnetic field, H_(z), alongthe z-direction, or SOC interconnect 404 with build-in exchanging biasfield along z-direction, bipolar switching is achieved in MI 401.

FIGS. 4D-E illustrate 3D views 440 and 450 for write and read mechanismsfor the TMD based spin orbit coupling memory device, respectively, inaccordance with some embodiments. Here, an interconnect 441 is formedadjacent to magnet 403. The interconnect can comprise any suitableconducting material such as Cu, Al, W, Ag, Au, Fe, Graphene, Co, andtheir alloys. The magnetization of MI 401 can be manipulated by SOCmaterial through spin-orbit torque. If magnetic polarization of fixedmagnet 403 and spin filter of layers 401/402 MI/TMD are aligned, thedevice is ON. If these two are opposite, the device is OFF.

During write operation, charge current I_(w) 445 passes through SOCmaterial of interconnect 404. During read operation, current 456 passesthrough interconnect 441, fixed magnet 403 and the spin filter stackcomprising layers 401 and 402. Here, the spin filter stack allows for anon-tunneling junction without the need for tunneling dielectricmaterial (e.g., MgO). Therefore, the breakdown of tunneling dielectricmaterial during readout may not be a concern in the memory structure ofthe various embodiments. The non-tunneling junction of the variousembodiments does not use high TMR as used in MTJ based devices. In someembodiments, the spin filter stack has high on/off ratio that is similarto the on/off ratio of TMD-based MOS devices. In some embodiments, thespin filter stack can also be used as an interconnect.

FIGS. 5A-B illustrate a 3D view 500 and a corresponding cross-sectionalview 520, respectively, of a TMD based spin orbit coupling memorydevice, in accordance with some other embodiments. Compared to thedevices of FIGS. 4A-B, here the devices are flipped along the z-axissuch that the SOC interconnect 404 is at the top while the magnet 403 isat the top. Operation wise, and technical effect wise, the devices ofFIGS. 5A-B operate same as the devices of FIGS. 4A-B.

FIGS. 6A-C illustrate mechanisms for switching an out-of-plane TMD basedspin orbit coupling memory device (e.g. device of FIG. 4A), inaccordance with some embodiments.

FIG. 6A illustrates a non-tunneling magnetic memory device (e.g., thenon-tunneling memory device of FIG. 4A) where the non-tunneling magneticstack 421 is disposed on a spin orbit torque electrode 404, and where amagnetization 654 of the MI 401 (also referred to as storage layer 401)is in the same direction as a magnetization 656 of fixed magnet 403.Here, 623 a/b are contacts coupled to the SOC interconnect 404. In someembodiments, the direction of magnetization 654 of the storage layer 401and the direction of magnetization 656 of fixed magnet 403 are both inthe negative z-direction as illustrated in FIG. 6A. When themagnetization 654 of the storage layer 401 is in the same direction as amagnetization 656 of the fixed magnet 403, the non-tunneling memorydevice of FIG. 4A is in a low resistance state. Conversely, when themagnetization 654 of the storage layer 401 is in the opposite directionas a magnetization 656 of fixed magnet 403, the non-tunneling memorydevice of FIG. 4A is in a high resistance state.

FIG. 6B illustrates a SOT memory device (e.g., the non-tunneling memorydevice of FIG. 4A) switched to a high resistance state. In anembodiment, a reversal in the direction of magnetization 654 of thestorage layer 401 in FIG. 6B compared to the direction of magnetization654 of the storage layer 401 is brought about by (a) inducing a spinhall current 668 in the spin orbit torque electrode 404 in they-direction and (b) by applying a spin torque transfer current 670,i_(STTM), (by applying a positive voltage at terminal B with respect toground C), and/or (c) by applying an external magnetic field, H_(y), inthe y-direction.

In an embodiment, a charge current 660 is passed through the spin orbittorque electrode 404 in the negative y-direction (by applying a positivevoltage at terminal A with respect to ground C). In response to thecharge current 660, an electron current 662 flows in the positivey-direction. The electron current 660 includes electrons with twoopposite spin orientations and experience a spin dependent scatteringphenomenon in the spin orbit torque electrode 404.

The electron current 662 includes electrons with two opposing spinorientations, a type I electron 666, having a spin oriented in thenegative x-direction and a type II electron 664 having a spin orientedin the positive x-direction. In some embodiments, electrons constitutingthe electron current 662 experience a spin dependent scatteringphenomenon in the spin orbit torque electrode 404. The spin dependentscattering phenomenon is brought about by a spin-orbit interactionbetween the nucleus of the atoms in the spin orbit torque electrode 404and the electrons in the electron current 662. The spin dependentscattering phenomenon causes type I electrons 666, whose spins areoriented in the negative x-direction, to be deflected upwards towards anuppermost portion of the spin orbit torque electrode 404 and type IIelectrons 664 whose spins are oriented in the positive x-direction to bedeflected downwards towards a lowermost portion of the spin orbit torqueelectrode 404.

The separation between the type I electron spin angular moment 666 andthe type II electron spin angular moment 664 induces a polarized spindiffusion current 668 in the spin orbit torque electrode 404. In someembodiments, the polarized spin diffusion current 568 is directedupwards toward the MI 401 of the non-tunneling memory device of FIG. 4A.The polarized spin diffusion current 668 induces a spin hall torque onthe magnetization 654 of the MI 401. The spin Hall torque rotates themagnetization 654 to a temporary state pointing in the negativex-direction. In some embodiments, to complete the magnetization reversalprocess an additional torque is applied. The i_(STTM) current 670flowing through the non-tunneling magnetic memory device of FIG. 4Aexerts an additional torque on the magnetization 654 of the storagelayer 401. The combination of spin hall torque and spin transfer torquecauses flipping of magnetization 654 in the storage layer 401 from theintermediate magnetization state (negative x-direction) to a positivez-direction illustrated in FIG. 6B. In some embodiments, an additionaltorque can be exerted on the storage layer 401 by applying an externalmagnetic field, H_(y), in the y-direction, as illustrated in FIG. 6B,instead of applying an i_(STTM) current 670.

FIG. 6C illustrates a SOT memory device switched to a low resistancestate. In an embodiment, a reversal in the direction of magnetization654 of the storage layer 401 in FIG. 6C compared to the direction ofmagnetization 654 of the storage layer 401 in FIG. 6B is brought aboutby (a) reversing the direction of the spin Hall current 668 in the spinorbit torque electrode 404 and (b) by reversing the direction of thei_(STTM) current 670, and/or (c) by reversing the direction of theexternal magnetic field, H_(y). While the embodiments of FIGS. 6A-Cillustrate an example of device operation using perpendicular orout-of-plane magnetizations, the same concepts also apply when layers orstructures 401 and 403 have in-plane magnetizations.

FIG. 7 illustrates a cross-sectional view of TMD based spin orbitcoupling memory device coupled to a transistor and a bit line, accordingto some embodiments.

In an embodiment, the transistor 700 has a source region 702, a drainregion 704 and a gate 706. The transistor 700 (e.g., n-type transistorMN) further includes a gate contact 714 disposed above and electricallycoupled to the gate 706, a source contact 716 disposed above andelectrically coupled to the source region 702, and a drain contact 718disposed above and electrically coupled to the drain region 704 as isillustrated in FIG. 7A. In some embodiments, an SOT memory device suchas an SOT non-tunneling memory device of FIG. 4A/5A is disposed abovethe transistor 700.

In some embodiments, the SOT memory device of FIG. 4A includes a spinorbit torque electrode, such as spin orbit torque electrode 404, anon-tunneling junction memory device such as device stack 421 disposedon the spin orbit torque electrode 404, and a conductive interconnectstructure such as conductive interconnect structure 441 (e.g., structure708A/B disposed on and coupled to the device stack 421. In someembodiments, the spin orbit torque electrode 404 is disposed on thedrain contact 718 of the transistor 700.

In some embodiments, the SOT non-tunneling memory device of FIG. 4A(e.g., which includes non-tunneling memory stack 421) includesindividual functional layers that are described in association withFIGS. 4A-C. In some embodiments, the spin orbit torque electrode 404 hasa length, LSOT that is less than a distance of separation, L_(DS)between the drain contact 718 and the source contact 716. In someembodiments, a portion of the spin orbit torque electrode 404 extendsabove the gate electrode 712 and the gate contact 714. In someembodiments, a portion of the spin orbit torque electrode 404 extendsover the gate electrode 712. In some embodiments, the spin orbit torqueelectrode 404 is in a first y-z plane as illustrated in FIG. 4A.

In some embodiments, the gate contact 714 is directly below the spinorbit torque electrode 404. In some embodiments, a word-line (WL)contact is disposed onto the gate contact 714 on a second y-z planebehind (into the page) the first y-z plane of the spin orbit torqueelectrode 404. In some embodiments, the spin orbit torque electrode 404that may not contact the word-line contact is disposed on the gateelectrode 712.

In some embodiments, transistor 700 associated with substrate 701 is ametal-oxide-semiconductor field-effect transistor (MOSFET or simply MOStransistors), fabricated on the substrate 701. In various embodiments ofthe present disclosure, the transistor 700 may be planar transistors,nonplanar transistors, or a combination of both. Nonplanar transistorsinclude FinFET transistors such as double-gate transistors and tri-gatetransistors, and wrap-around or all-around gate transistors such asnanoribbon and nanowire transistors. In an embodiment, the transistor700 is a tri-gate transistor.

In some embodiments, a voltage V_(DS) is applied between the bit-line(BL) 730 and the source-line (SL) 740 and a word-line 770 is energizedabove a threshold voltage, V_(TH) on the transistor 700. In someembodiments, an electron current (spin hall current) flows through thespin orbit torque electrode 404 and causes a spin diffusion current toflow toward the SOT non-tunneling memory device of FIG. 4A. The spindiffusion current exerts a torque on the magnetization of the MI 401.

In some embodiments, by applying a voltage V_(DS) between bit-line 730and source-line 740, current can flow through the SOT non-tunnelingmemory device of FIG. 4A. In some embodiments, a voltage V_(DS) that isequal to or greater than the threshold voltage V_(TS) is enough togenerate spin polarized current through the non-tunneling stack 421. Insome embodiments, the spin transfer torque current flowing through thenon-tunneling 421 also imparts torque to the MI 401 adding to the torquefrom the spin diffusion current. In some embodiments, the combinedeffect of the spin transfer torque and the spin diffusion torque canswitch the magnetization of the MI 401. In some embodiments, byreversing the polarity of the voltage V_(DS), and applying a voltagethat meets or exceeds a threshold voltage, the direction ofmagnetization of the MI 401 is switched back to a previousconfiguration.

In some embodiments, by applying a voltage between a bit-line 730 andsource-line 740, and by applying a voltage above a threshold voltage,V_(TH) on the word-line 770 of the transistor 700, SOT non-tunnelingmemory device of FIG. 4A can undergo magnetization switching without theneed for an additional voltage source (e.g. a second transistor). Insome embodiments, implementing an SOT non-tunneling memory device ofFIG. 4A above a transistor can increase the number of SOT non-tunnelingmemory devices of FIG. 4A in a given area of a die by at least a factorof two.

In some embodiments, the underlying substrate 701 represents a surfaceused to manufacture integrated circuits. In some embodiments, thesubstrate 701 includes a suitable semiconductor material such as but notlimited to, single crystal silicon, polycrystalline silicon and siliconon insulator (SOI). In another embodiment, the substrate 701 includesother semiconductor materials such as germanium, silicon germanium, or asuitable group III-V or group III-N compound. The substrate 701 may alsoinclude semiconductor materials, metals, dopants, and other materialscommonly found in semiconductor substrates.

In some embodiments, the transistor 700 includes a gate stack formed ofat least two layers, a gate dielectric layer 710 and a gate electrodelayer 712. The gate dielectric layer 710 may include one layer or astack of layers. The one or more layers may include silicon oxide,silicon dioxide (SiO₂) and/or a high-k dielectric material. The high-kdielectric material may include elements such as hafnium, silicon,oxygen, titanium, tantalum, lanthanum, aluminum, zirconium, barium,strontium, yttrium, lead, scandium, niobium, and zinc. Examples ofhigh-k materials that may be used in the gate dielectric layer include,but are not limited to, hafnium oxide, hafnium silicon oxide, lanthanumoxide, lanthanum aluminum oxide, zirconium oxide, zirconium siliconoxide, tantalum oxide, titanium oxide, barium strontium titanium oxide,barium titanium oxide, strontium titanium oxide, yttrium oxide, aluminumoxide, lead scandium tantalum oxide, and lead zinc niobate. In someembodiments, an annealing process may be carried out on the gatedielectric layer 710 to improve its quality when a high-k material isused.

The gate electrode layer 712 of the transistor 700 is formed on the gatedielectric layer 710 and may comprise of at least one P-typework-function metal or N-type work-function metal, depending on whetherthe transistor is to be a PMOS or an NMOS transistor. In someembodiments, the gate electrode layer 712 may comprise of a stack of twoor more metal layers, where one or more metal layers are work-functionmetal layers and at least one metal layer is a conductive fill layer.

For a PMOS transistor, metals that may be used for the gate electrodelayer 712 include, but are not limited to, ruthenium, palladium,platinum, cobalt, nickel, and conductive metal oxides, e.g., rutheniumoxide. A P-type metal layer will enable the formation of a PMOS gateelectrode layer 712 with a work-function that is between about 4.9 eVand about 5.2 eV. For an NMOS transistor, metals that may be used forthe gate electrode layer 712 include, but are not limited to, hafnium,zirconium, titanium, tantalum, aluminum, alloys of these metals, andcarbides of these metals such as hafnium carbide, zirconium carbide,titanium carbide, tantalum carbide, and aluminum carbide. An N-typemetal layer will enable the formation of an NMOS gate electrode layer712 with a work-function that is between about 3.9 eV and about 4.2 eV.

In some embodiments, the gate electrode layer 712 may comprise aU-shaped structure that includes a bottom portion substantially parallelto the surface of the substrate and two sidewall portions that aresubstantially perpendicular to the top surface of the substrate. Inanother embodiment, at least one of the metal layers that form the gateelectrode layer 712 may simply be a planar layer that is substantiallyparallel to the top surface of the substrate and does not includesidewall portions substantially perpendicular to the top surface of thesubstrate. In some embodiments of the present disclosure, the gateelectrode layer 712 may comprise of a combination of U-shaped structuresand planar, non-U-shaped structures. For example, the gate electrodelayer 712 may comprise of one or more U-shaped metal layers formed atopone or more planar, non-U-shaped layers.

In some embodiments, a pair of gate dielectric layers 710 may be formedon opposing sides of the gate stack that bracket the gate stack. Thegate dielectric layer 710 may be formed from a material such as siliconnitride, silicon oxide, silicon carbide, silicon nitride doped withcarbon, and silicon oxynitride. Processes for forming sidewall spacersare well known in the art and generally include deposition and etchingprocess operations. In some embodiments, a plurality of spacer pairs maybe used, for instance, two pairs, three pairs, or four pairs of sidewallspacers may be formed on opposing sides of the gate stack.

In some embodiments, source region 702 and drain region 704 are formedwithin the substrate adjacent to the gate stack of the transistor 700.The source region 702 and drain region 704 are generally formed usingeither an implantation/diffusion process or an etching/depositionprocess. In the former process, dopants such as boron, aluminum,antimony, phosphorous, or arsenic may be ion-implanted into thesubstrate to form the source region 702 and drain region 704. Anannealing process that activates the dopants and causes them to diffusefurther into the substrate typically follows the ion implantationprocess. In the latter process, the substrate may first be etched toform recesses at the locations of the source and drain regions. Anepitaxial deposition process may then be carried out to fill therecesses with material that is used to fabricate the source region 702and drain region 704. In some embodiments, the source region 702 anddrain region 704 may be fabricated using a silicon alloy such as silicongermanium or silicon carbide. In some embodiments, the epitaxiallydeposited silicon alloy may be doped in-situ with dopants such as boron,arsenic, or phosphorous. In some embodiments, the source region 702 anddrain region 704 may be formed using one or more alternate semiconductormaterials such as germanium or a suitable group III-V compound. In someembodiments, one or more layers of metal and/or metal alloys may be usedto form the source region 702 and drain region 704.

In some embodiments, the gate contact 714 and drain contact 718 of thetransistor 700 are disposed in a first dielectric layer 720 disposedabove the substrate 701. In some embodiments, the spin orbit torqueelectrode 404 is disposed in a second dielectric layer 722 disposed onthe first dielectric layer 720. In some embodiments, a third dielectriclayer 724 is disposed on the second dielectric layer 722. In someembodiments, a fourth dielectric layer 726 is disposed on the thirddielectric layer 724. In some embodiments, a source contact 716 ispartially disposed in the fourth dielectric layer 726, partiallydisposed in the third dielectric layer 724, partially disposed in thesecond dielectric layer 722 and partially disposed on the firstdielectric layer 720. In some embodiments, the spin orbit torqueelectrode contact is disposed in the third dielectric layer 724 on thespin orbit torque electrode 404. In some embodiments, the conductiveinterconnect structure such as conductive interconnect structure 708A/Bdisposed in the fourth dielectric layer 726.

In the illustrated embodiment of FIG. 6A, the gate contact 714 is formedin poly region; drain contact 718 is formed in active, poly, and Metal 0(M0); SOT or SHE electrode 404 is formed in Via 0-1 layer; MTJ 421 isformed in Metal 1 (M1) and Via 1-2; contract 708A is formed in Metal 2(M2) and Via 2-3; and conductor 708B is formed in Metal 3 (M3).

In some embodiments, the non-tunneling magnetic junction stack 421 isformed in the metal 3 (M3) region. In some embodiments, the MI layer 403couples to SOC electrode 404. In some embodiments, fixed magnet 403communicatively couples to the bit-line (BL) via SOC electrode 404through Via 3-4 (e.g., via connecting metal 4 region to metal 4 (M4)).In this example embodiments, the bit-line is formed on M4. In someembodiments, fixed magnet 403 directly couples to BL 730. In someembodiments, fixed magnet 403 indirectly couples to BL 730. For example,SAF layer(s) not shown may be formed over fixed magnet 403 and anelectrode over the SAF layer(s) may be coupled to BL 730. Effectively,BL 730 is coupled to fixed magnet 403.

In some embodiments, an n-type transistor MN is formed in the frontendof the die while the SOC electrode 404 is located in the backend of thedie. Here, the term “backend” generally refers to a section of a diewhich is opposite of a “frontend” and where an IC (integrated circuit)package couples to IC die bumps. For example, high level metal layers(e.g., metal layer 6 and above in a ten-metal stack die) andcorresponding vias that are closer to a die package are considered partof the backend of the die. Conversely, the term “frontend” generallyrefers to a section of the die that includes the active region (e.g.,where transistors are fabricated) and low-level metal layers andcorresponding vias that are closer to the active region (e.g., metallayer 5 and below in the ten-metal stack die example). In someembodiments, the SOC electrode 404 is located in the backend metallayers or via layers for example, in Via 3. In some embodiments, theelectrical connectivity to the device is obtained in layers M0 and M4 orM1 and M5 or any set of two parallel interconnects. In some embodiments,the MTJ 421 is formed in metal 2 (M2) and metal 1 (M1) layer regionand/or Via 1-2 region. In some embodiments, the SOC electrode 404 isformed in the metal 1 region.

While the embodiment of FIG. 7 is illustrated with reference to FIG. 4Amemory device, the memory device of Fig. SA can also be used andappropriate changes to the interconnects/vias can be made for properconnection.

FIG. 8 illustrates a flowchart 800 of a method for forming a TMD basedspin orbit coupling memory device, according to some embodiments of thedisclosure. The various operations here can be organized in any order.Some blocks can be performed in parallel to other blocks.

At block 801, a spin filter is formed by fabricating a stack comprisingMI 401 material and TMD 402, wherein MI 401 has a first magnetization(e.g., out-of-plane relative to a plane of a device). In someembodiments, MI 401 comprises one or more of: EuS, EuO, YIG, TmIG, andGaMnAs. In some embodiments, TMD 402 comprises one or more of: MoS₂,MoSe₂, WS₂, WSe₂, PtS₂, PtSe₂, WTe₂, and MoTe₂, and graphene.

At block 802, a fixed magnet 403 is formed with second magnetization,wherein fixed magnet 403 is adjacent to the spin filter. For example,fixed magnet 403 is coupled to TMD 402 of the spin filter. In someembodiments, fixed magnet 403 includes one or more of: Co, Ni, Fe,CoFeB, FeB, CoFe, LaSrMoO₃(LSMO), Co/Pt, CoFeGd, and ferromagneticsemi-metal such as Weyl, and Heusler alloy such as Cu₂MnAl, Cu₂MnIn,Cu₂MnSn. Here, the TMD 402 and MI 401 together forms a free magnet.

At block 803, SOC interconnect 404 is formed, wherein SOC interconnect404 is adjacent to MI 401. In some embodiments, SOC interconnect 404comprises one or more of: Pt, Ta, W, WO_(x), CuBi, BiO_(x),LaAlO₃/SrTiO₃, Bi₂Se₃, Bi₂Sb₃, SrIrO₃. As such, a magnetic device isformed using spin filter.

FIG. 9 illustrates a smart device or a computer system or a SoC(System-on-Chip) with one or more SOT non-tunneling memory devices suchas those described in FIGS. 4-7, according to some embodiments. FIG. 9illustrates a block diagram of an embodiment of a mobile device in whichflat surface interface connectors could be used. In some embodiments,computing device 1600 represents a mobile computing device, such as acomputing tablet, a mobile phone or smart-phone, a wireless-enablede-reader, or other wireless mobile device. It will be understood thatcertain components are shown generally, and not all components of such adevice are shown in computing device 1600.

In some embodiments, computing device 1600 includes first processor 1610with one or more SOT non-tunneling memory devices such as thosedescribed in FIGS. 4-7, according to some embodiments discussed. Otherblocks of the computing device 1600 may also include one or more SOTnon-tunneling memory devices such as those described in FIGS. 4-7,according to some embodiments. The various embodiments of the presentdisclosure may also comprise a network interface within connectivity1670 such as a wireless interface so that a system embodiment may beincorporated into a wireless device, for example, cell phone or personaldigital assistant.

In some embodiments, processor 1610 can include one or more physicaldevices, such as microprocessors, application processors,microcontrollers, programmable logic devices, or other processing means.The processing operations performed by processor 1610 include theexecution of an operating platform or operating system on whichapplications and/or device functions are executed. The processingoperations include operations related to I/O (input/output) with a humanuser or with other devices, operations related to power management,and/or operations related to connecting the computing device 1600 toanother device. The processing operations may also include operationsrelated to audio I/O and/or display I/O.

In some embodiments, computing device 1600 includes audio subsystem1620, which represents hardware (e.g., audio hardware and audiocircuits) and software (e.g., drivers, codecs) components associatedwith providing audio functions to the computing device. Audio functionscan include speaker and/or headphone output, as well as microphoneinput. Devices for such functions can be integrated into computingdevice 1600 or connected to the computing device 1600. In oneembodiment, a user interacts with the computing device 1600 by providingaudio commands that are received and processed by processor 1610.

In some embodiments, computing device 1600 comprises display subsystem1630. Display subsystem 1630 represents hardware (e.g., display devices)and software (e.g., drivers) components that provide a visual and/ortactile display for a user to interact with the computing device 1600.Display subsystem 1630 includes display interface 1632, which includesthe particular screen or hardware device used to provide a display to auser. In one embodiment, display interface 1632 includes logic separatefrom processor 1610 to perform at least some processing related to thedisplay. In one embodiment, display subsystem 1630 includes a touchscreen (or touch pad) device that provides both output and input to auser.

In some embodiments, computing device 1600 comprises I/O controller1640. I/O controller 1640 represents hardware devices and softwarecomponents related to interaction with a user. I/O controller 1640 isoperable to manage hardware that is part of audio subsystem 1620 and/ordisplay subsystem 1630. Additionally, I/O controller 1640 illustrates aconnection point for additional devices that connect to computing device1600 through which a user might interact with the system. For example,devices that can be attached to the computing device 1600 might includemicrophone devices, speaker or stereo systems, video systems or otherdisplay devices, keyboard or keypad devices, or other I/O devices foruse with specific applications such as card readers or other devices.

As mentioned above, I/O controller 1640 can interact with audiosubsystem 1620 and/or display subsystem 1630. For example, input througha microphone or other audio device can provide input or commands for oneor more applications or functions of the computing device 1600.Additionally, audio output can be provided instead of, or in addition todisplay output. In another example, if display subsystem 1630 includes atouch screen, the display device also acts as an input device, which canbe at least partially managed by I/O controller 1640. There can also beadditional buttons or switches on the computing device 1600 to provideI/O functions managed by I/O controller 1640.

In some embodiments, I/O controller 1640 manages devices such asaccelerometers, cameras, light sensors or other environmental sensors,or other hardware that can be included in the computing device 1600. Theinput can be part of direct user interaction, as well as providingenvironmental input to the system to influence its operations (such asfiltering for noise, adjusting displays for brightness detection,applying a flash for a camera, or other features).

In some embodiments, computing device 1600 includes power management1650 that manages battery power usage, charging of the battery, andfeatures related to power saving operation. Memory subsystem 1660includes memory devices for storing information in computing device1600. Memory can include nonvolatile (state does not change if power tothe memory device is interrupted) and/or volatile (state isindeterminate if power to the memory device is interrupted) memorydevices. Memory subsystem 1660 can store application data, user data,music, photos, documents, or other data, as well as system data (whetherlong-term or temporary) related to the execution of the applications andfunctions of the computing device 1600.

Elements of embodiments are also provided as a machine-readable medium(e.g., memory 1660) for storing the computer-executable instructions(e.g., instructions to implement any other processes discussed herein).The machine-readable medium (e.g., memory 1660) may include, but is notlimited to, flash memory, optical disks, CD-ROMs, DVD ROMs, RAMs,EPROMs, EEPROMs, magnetic or optical cards, phase change memory (PCM),or other types of machine-readable media suitable for storing electronicor computer-executable instructions. For example, embodiments of thedisclosure may be downloaded as a computer program (e.g., BIOS) whichmay be transferred from a remote computer (e.g., a server) to arequesting computer (e.g., a client) by way of data signals via acommunication link (e.g., a modem or network connection).

In some embodiments, computing device 1600 comprises connectivity 1670.Connectivity 1670 includes hardware devices (e.g., wireless and/or wiredconnectors and communication hardware) and software components (e.g.,drivers, protocol stacks) to enable the computing device 1600 tocommunicate with external devices. The computing device 1600 could beseparate devices, such as other computing devices, wireless accesspoints or base stations, as well as peripherals such as headsets,printers, or other devices.

Connectivity 1670 can include multiple different types of connectivity.To generalize, the computing device 1600 is illustrated with cellularconnectivity 1672 and wireless connectivity 1674. Cellular connectivity1672 refers generally to cellular network connectivity provided bywireless carriers, such as provided via GSM (global system for mobilecommunications) or variations or derivatives, CDMA (code divisionmultiple access) or variations or derivatives, TDM (time divisionmultiplexing) or variations or derivatives, or other cellular servicestandards. Wireless connectivity (or wireless interface) 1674 refers towireless connectivity that is not cellular and can include personal areanetworks (such as Bluetooth, Near Field, etc.), local area networks(such as Wi-Fi), and/or wide area networks (such as WiMax), or otherwireless communication.

In some embodiments, computing device 1600 comprises peripheralconnections 1680. Peripheral connections 1680 include hardwareinterfaces and connectors, as well as software components (e.g.,drivers, protocol stacks) to make peripheral connections. It will beunderstood that the computing device 1600 could both be a peripheraldevice (“to” 1682) to other computing devices, as well as haveperipheral devices (“from” 1684) connected to it. The computing device1600 commonly has a “docking” connector to connect to other computingdevices for purposes such as managing (e.g., downloading and/oruploading, changing, synchronizing) content on computing device 1600.Additionally, a docking connector can allow computing device 1600 toconnect to certain peripherals that allow the computing device 1600 tocontrol content output, for example, to audiovisual or other systems.

In addition to a proprietary docking connector or other proprietaryconnection hardware, the computing device 1600 can make peripheralconnections 1680 via common or standards-based connectors. Common typescan include a Universal Serial Bus (USB) connector (which can includeany of a number of different hardware interfaces), DisplayPort includingMiniDisplayPort (MDP), High Definition Multimedia Interface (HDMI),Firewire, or other types.

Reference in the specification to “an embodiment,” “one embodiment,”“some embodiments,” or “other embodiments” means that a particularfeature, structure, or characteristic described in connection with theembodiments is included in at least some embodiments, but notnecessarily all embodiments. The various appearances of “an embodiment,”“one embodiment,” or “some embodiments” are not necessarily allreferring to the same embodiments. If the specification states acomponent, feature, structure, or characteristic “may,” “might,” or“could” be included, that particular component, feature, structure, orcharacteristic is not required to be included. If the specification orclaim refers to “a” or “an” element, that does not mean there is onlyone of the elements. If the specification or claims refer to “anadditional” element, that does not preclude there being more than one ofthe additional element.

Furthermore, the particular features, structures, functions, orcharacteristics may be combined in any suitable manner in one or moreembodiments. For example, a first embodiment may be combined with asecond embodiment anywhere the particular features, structures,functions, or characteristics associated with the two embodiments arenot mutually exclusive.

While the disclosure has been described in conjunction with specificembodiments thereof, many alternatives, modifications and variations ofsuch embodiments will be apparent to those of ordinary skill in the artin light of the foregoing description. The embodiments of the disclosureare intended to embrace all such alternatives, modifications, andvariations as to fall within the broad scope of the appended claims.

In addition, well known power/ground connections to integrated circuit(IC) chips and other components may or may not be shown within thepresented figures, for simplicity of illustration and discussion, and soas not to obscure the disclosure. Further, arrangements may be shown inblock diagram form in order to avoid obscuring the disclosure, and alsoin view of the fact that specifics with respect to implementation ofsuch block diagram arrangements are highly dependent upon the platformwithin which the present disclosure is to be implemented (i.e., suchspecifics should be well within purview of one skilled in the art).Where specific details (e.g., circuits) are set forth in order todescribe example embodiments of the disclosure, it should be apparent toone skilled in the art that the disclosure can be practiced without, orwith variation of, these specific details. The description is thus to beregarded as illustrative instead of limiting.

An abstract is provided that will allow the reader to ascertain thenature and gist of the technical disclosure. The abstract is submittedwith the understanding that it will not be used to limit the scope ormeaning of the claims. The following claims are hereby incorporated intothe detailed description, with each claim standing on its own as aseparate embodiment.

We claim:
 1. An apparatus comprising: a stack comprising a magneticinsulative material and a transition metal dichalcogenide (TMD), whereinthe magnetic insulating material has a first magnetization; a magnetwith a second magnetization, wherein the magnet is adjacent to the TMDof the stack; and an interconnect comprising a spin orbit material,wherein the interconnect is adjacent to the stack.
 2. The apparatus ofclaim 1, wherein the first magnetization and the second magnetizationare perpendicular magnetization relative to a plane of a device; orwherein the first magnetization and the second magnetization arein-plane magnetization relative to a plane of the device.
 3. Theapparatus of claim 1, wherein magnet comprises a material which includesone or more of: Co, Fe, Ni, or O.
 4. The apparatus of claim 1, whereinthe magnet is one of a paramagnet or ferromagnet.
 5. The apparatus ofclaim 1, wherein the magnet comprises a material which includes one ormore of: Pt, Pd, W, Ce, Al, Li, Mg, Na, Cr, O, Co, Dy, Er, Eu, Gd, Fe,Nd, K, Pr, Sm, Tb, Tm, or V.
 6. The apparatus of claim 1, wherein themagnet comprises one or a combination of materials which includes one ormore of: a Heusler alloy, Co, Fe, Ni, Gd, B, Ge, Ga, permalloy, orYttrium Iron Garnet (YIG), and wherein the Heusler alloy is a materialwhich includes one or more of: Cu, Mn, Al, In, Sn, Ni, Sb, Ga, Co, Fe,Si, Pd, Sb, Si, V, or Ru.
 7. The apparatus of claim 1, wherein themagnetic insulative material comprises one or more of: Eu, S, O, Y, Fe,Tm, Ga, Mn, or As.
 8. The apparatus of claim 1, wherein the TMDcomprises one or more of: Mo, S, Se, W, Pt, Te, or graphene.
 9. Theapparatus of claim 1, wherein the spin orbit material includes one ormore of: β-Tantalum (β-Ta), Ta, β-Tungsten (β-W), W, Platinum (Pt),Copper (Cu) doped with elements including on of Iridium, Bismuth orelements of 3d, 4d, 5d and 4f, 5f periodic groups, Ti, S, W, Mo, Se, B,Sb, Re, La, C, P, La, As, Sc, O, Bi, Ga, Al, Y, In, Ce, Pr, Nd, F, Ir,Mn, Pd, or Fe.
 10. The apparatus of claim 1, wherein: the spin orbitmaterial includes one of: a 2D material, a 3D material, anantiferromagnetic (AFM) material, or an AFM material doped with adopant; the 3D material is thinner than the 2D material; or the dopantincludes one of: Co, Fe, Ni, Mn, Ga, Fe, or Bct-Ru.
 11. An apparatuscomprising: a bit-line; a word-line; a source-line; an interconnectcomprising spin orbit material; a transistor having a gate terminalcoupled to the word-line, one of a source or drain terminal coupled tothe source-line; and one of the source or drain terminal coupled to theinterconnect; a stack comprising a magnetic insulative material and atransition metal dichalcogenide (TMD), wherein the magnetic insulativematerial has a first magnetization, wherein the interconnect is adjacentto the stack; and a magnet with a second magnetization, wherein themagnet is adjacent to the TMD of the stack, wherein the bit-line isadjacent to the magnet.
 12. The apparatus of claim 11, wherein the firstmagnetization and the second magnetization are perpendicularmagnetization relative to a plane of a device; or wherein the first andsecond magnetization are in-plane magnetization relative to a plane of adevice.
 13. The apparatus of claim 11, wherein the magnet is one of aparamagnet or ferromagnet.
 14. The apparatus of claim 11, wherein themagnet comprises a material which includes one or more of: Ni, Pt, Pd,W, Ce, Al, Li, Mg, Na, Cr, 0, Co, Dy, Er, Eu, Gd, Fe, Nd, K, Pr, Sm, Tb,Tm, or V.
 15. The apparatus of claim 11, wherein the magnet comprisesone or a combination of materials which includes one or more of: aHeusler alloy, Co, Fe, Ni, Gd, B, Ge, Ga, permalloy, or Yttrium IronGarnet (YIG), and wherein the Heusler alloy is a material which includesone or more of: Cu, Mn, Al, In, Sn, Ni, Sb, Ga, Co, Fe, Si, Pd, Sb, Si,V, or Ru.
 16. The apparatus of claim 11, wherein the magnetic insulativematerial comprises one or more of: Eu, S, 0, Y, Fe, Tm, Ga, Mn, or As,and wherein the TMD comprises one or more of: Mo, S, Se, W, Pt, Te, orgraphene.
 17. The apparatus of claim 11, wherein the spin orbit materialincludes one or more of: β-Tantalum (β-Ta), Ta, β-Tungsten (β-W), W,Platinum (Pt), Copper (Cu) doped with elements including on of Iridium,Bismuth or elements of 3d, 4d, 5d and 4f, 5f periodic groups, Ti, S, W,Mo, Se, B, Sb, Re, La, C, P, La, As, Sc, O, Bi, Ga, Al, Y, In, Ce, Pr,Nd, F, Ir, Mn, Pd, or Fe.
 18. A system comprising: a memory; a processorcoupled to the memory, the processor including a spin filter devicecomprising: a stack comprising a magnetic insulative material and atransition metal dichalcogenide (TMD), wherein the magnetic insulativematerial has a first magnetization; a magnet with a secondmagnetization, wherein the magnet is adjacent to the TMD of the stack;and an interconnect comprising a spin orbit material, wherein theinterconnect is adjacent to the stack; and a wireless interface to allowthe processor to communicate with another device.
 19. The system ofclaim 18, wherein: the magnetic insulative material comprises one ormore of: Eu, S, O, Y, Fe, Tm, Ga, Mn, or As; and the TMD comprises oneor more of: Mo, S, Se, W, Pt, Te, or graphene; the magnet comprises amaterial which includes one or more of: Pt, Pd, W, Ce, Al, Li, Mg, Na,Cr, 0, Co, Dy, Er, Eu, Gd, Fe, Nd, K, Pr, Sm, Tb, Tm, or V; or themagnet comprises one or a combination of materials which includes one ormore of: a Heusler alloy, Co, Fe, Ni, Gd, B, Ge, Ga, permalloy, orYttrium Iron Garnet (YIG).
 20. The system of claim 18, wherein the spinorbit material includes one or more of: β-Tantalum (β-Ta), Ta,(β-Tungsten (β-W), W, Platinum (Pt), Copper (Cu) doped with elementsincluding on of Iridium, Bismuth or elements of 3d, 4d, 5d and 4f, 5fperiodic groups, Ti, S, W, Mo, Se, B, Sb, Re, La, C, P, La, As, Sc, O,Bi, Ga, Al, Y, In, Ce, Pr, Nd, F, Ir, Mn, Pd, or Fe.